Research on cysteine
Cysteine and cysteine-containing peptides from meat
enhance the absorption of non-heme iron in man. The
addition of 210 mg of cysteine to a maize meal
approximately doubles iron absorption. Cysteine is
thought to increase the absorption of non-heme iron
by binding the iron through its thiol group. The protein
metallothionein contains 12 cysteines out of 74 amino
acids. Lucca et al. [33] and Goto et al. [25] discovered a
gene in basmati rice that enhances the formation of
metallothionein. By overexpressing metallothionein in
rice, they increased the cysteine residue content of the
soluble seed proteins about seven-fold and the phytase
level in the grains about 130-fold. The phytase activity
was sufficient to completely degrade phytic acid in
a simulated digestion experiment [33]. Iron-enriched
rice with phytase and cysteine-containing peptides has
a great potential for substantially improving iron
nutrition.